A Coupled Two-Way Fluid-Structure Interaction Analysis for the Dynamics of a Partially Confined Cantilevered Pipe Under Simultaneous Internal and External Axial Flow in Opposite Directions

This paper presents the results of a coupled two-way fluid-structure interaction analysis of a slender flexible vertical cantilevered pipe hanging concentrically within a shorter rigid tube forming an annulus. The pipe is subjected to internal and annular flows simultaneously. This system has applications in brine production and salt-cavern hydrocarbon storage. In the present study, the fluid-structure problem is solved with a finite-volume-based CFD code for the fluid domain coupled to a finite-element-based CSM code for the structural domain. The numerical results obtained for the free-end displacement of the central pipe versus the annular/internal flow velocity ratio U_o/U_i are presented and compared with those obtained from experiment. The capability of the numerical model to predict the onset of the experimentally observed flutter instability in the system is also examined. This provides a better insight into the dynamics of the system.